This invention pertains to a chair, and more particularly to a chair used by secretaries, typists, etc., and having a concealed adjustment mechanism for adjusting the height of the chair back.
Generally, chairs having adjustable backs comprise a base, a seat supported by the base, a support member attached to the base and extending upwardly from the seat, and a back mounted on the support member. The back is generally movably secured to the support member so that the back can be adjusted vertically relative to the seat.
Chair back height adjustment mechanisms of prior art chairs have not been satisfactory since the backs have been difficult to adjust for the chair occupants. One example of such a prior art height adjustment mechanism is disclosed in U.S. Pat. No. 3,526,430. A concealed chair back height adjustment mechanism is disclosed wherein the occupant of the chair must pull forwardly on the top portion of the chair back in order to adjust the height of the chair back. Thus an occupant of the chair must reach over his shoulder to reach the top of the chair back and must then pull the chair back forwardly and simultaneously slide the back upwardly or downwardly to adjust it to a new position. It is inconvenient and uncomfortable for most people to assume the positions necessary to make these adjustments. Alternatively the occupant can leave the chair and adjust the back by pulling the top portion of the back forwardly and sliding the back to the new vertical position. The person must then reoccupy the chair to see if the back is adjusted to the proper height and, if further adjustment is needed, he must again leave the chair and repeat the procedure. What is therefore desired is to provide a chair height adjustment mechanism whereby the occupant of the chair can adjust the height of the back without leaving the chair. What is furthermore desired is to provide a chair back height adjustment mechanism whereby the chair back can be adjusted easily by a person occupying a chair.
Yet another problem with prior art height adjustment mechanisms for chair backs has been that when the chair is not occupied and someone pushes on the top of the chair back it is possible that the height of the chair back will be inadvertantly adjusted by the forward pressure on the top of the chair back. Such adjustments are of course undesirable. What is therefore desired is to provide a chair with an adjustable back wherein the back will retain its position despite application of forces to the top of the chair back.
Another problem with prior art adjustment mechanisms for chair backs has been that they are relatively complex and therefore relatively costly to manufacture. It is therefore desired to provide a chair back height adjustment mechanism which is simple and reliable and which is relatively inexpensive to manufacture.
A still further problem with prior art chair back height adjustment mechanism has been that they are exposed so that dust and dirt can collect on them and thereby prevent their proper preparation as well as make them unsightly. It is therefore desired to provide a height adjustment mechanism for a chair back which is concealed.